Numerous prior art processes have been proposed for the preparation of glycol esters of carboxylic acids by reacting an olefinically unsaturated compound such as ethylene and oxygen in the presence of a carboxylic acid and various catalyst systems including tellurium and other variable valent metal compounds together with a halogen source to provide halide ions in solution under oxidation conditions.
Literature articles namely, Kogyo Kagku Zassi, Vol. 73, page 1987 (1970) by M. Ogawa, C. Inone and R. Ishioka; Journ. Prakt. Chem., [4], Vol. 1, page 33 (1954) by H. Funk and Weiss and Angew. Chem. Ind. Ed. Eng. Vol. 10, page 73 (1971) by H. J. Arpe and H. Kuckertz show that tellurium tetrachloride adds across the carbon-carbon double bond in propylene to give substituted organyl tellurium trichloride, and in ethylene and in propylene, when the reagents are mixed in stoichiometric ratio, to give bis(2-haloalkyl)tellurium dichlorides respectively.
In an article by M. Ogawa, Bull. Chem. Soc. Japan, Vol. 41, page 3031 (1968) and the Angew. Chem. Ind. Ed. Eng. Vol. 10, (1971) article noted above there is described the thermal decomposition of bis(2-chloroalkyl)tellurium dichloride which when decomposed gave only olefins, various chloroalkanes, chloroolefins, hydrogen chloride and inorganic tellurium compounds and therefore provided no practical application for the preparation of glycol esters or the respective glycol such as ethylene or propylene glycol.
There is no prior art which describes the thermal decomposition of organic bromoalkyltellurium compounds or the bis(2-bromoalkyl)tellurium carboxylate compounds of the present invention.
Contrary to the prior art teaching and investigative findings, it has surprisingly been discovered that bis(2-bromoalkyl)tellurium dicarboxylate compounds can be thermally decomposed in an aliphatic monocarboxylic acid medium and oxygen to provide excellent yields of vicinal glycol esters such as ethylene glycol diacetate. In addition the reaction may be carried out in an acetonitrile solvent, which is inert to the reaction system, and the absence of oxygen to give a predominent amount of the bromoalkyl ester.